Stable-surface alloy steel



Patented June 10, 1930 UNITED STATES RALPH P. DIE VRIES, F NEWTONVILLE, NEW YORK STABLE-SURFACE ALLOY STEEL Io Drawing.

This invention relates to alloys of steel, mum resistance to scaling, higher percentages and more particularly to suchv alloys as are known to the trade as stable surface alloy steels. v

The main objects of my invention are to provide an alloy steel of new composition which will be resistant to scaling action at high temperatures and which shall have a fine grain, fair strength and good ductility when high percentages of silicon are the essential and in most cases the main ingredient of said alloy.

To the best of my knowledge it has never been possible to use for general engineering and structural purposes any alloy where aluminum and silicon taken together range from 4:% to 6%, for the reason that hitherto known alloys containing quantities of aluminum and silicon taken together in the proportions just mentioned cannot be manufactured into bars, strips, and other commercial grades of steel of suflicient strength and ductility. Although it has been proposed to use various other alloy metals with aluminum and silicon in the percentages mentioned, to produce malleability such that the steel after being cast into ingot form can be successfully rolled and worked, it has not been found that such alloys have the requisite strength and ductility to be useful for general engineering and structural purposes.

I have found that when silicon and aluminum taken together are present in the alloy in an amount from 4% to 6%, it is possible to greatly improve the product by forming an alloy through the addition of copper and chromium. The copper forms copper silicides with the silicon and forms a solid solution with the aluminum. Thus neither the silicon nor the aluminum is present in the alloy merely in mechanical mixture. The chromium functionsas a hardeningagent.

An alloy steel made in accordance with my invention may comprise chromium from 1.0% to-10.0%, silicon from 0.5% to 6.0%, aluminum from 0.2% to 6.0%, and copper from 0.5% to 5.0%. For satisfactory results, particularly with the lower ranges of chromium, the combined aluminum and silicon content should neverbe less than 2.5%. For maxi- Applieatlon filed January 20, 1926. Serial No. 82,611.

of silicon and aluminum taken together should be used throughout the whole range of chromium. But I have found that silicon and aluminum taken together should not be in excess of 6.2% of the allov. In the lower range of chromium the combined silicon and aluminum content is best kept at or above 5.0% and the copper content at least 2.0%, and may be profitably increased to the maximum for certain purposes. All proportions given are percentages of the whole by weight.

Typical examples of the alloy may be noted as having the following composition:

' Silicon 4 3 3 C Jopper Carbon Iron ent P eat P rcntP Balance Balance Balance Balance Alloys of this composition can be melted practically carbon free, but for some purposes may contain carbon as high as 1 The usual amount of manganese found in tool and structural steels may be present, or slightly greater amounts up to 1.5% may be used. Impurities and metalloids such as sulphur, phosphorus, etc., will be kept as low as possible,

and are included, as also the manganese when present, inthe iron balance above given.

Alloy steels made according to the above analysis are resistant to scaling action at high temperatures up to 17 00 F., and possess the further advantage that when thus exposed to high temperatures the oxide film remains more or less transparent and is very often a silvery white or other color than black. This is of great commercial advantage as it indicates the thinness of the film formed, thereby showing at once how resistant the steel is to the action of scaling.

For ease in meltingI may add the aluminum and co oer to the iron as an aluminumabove their critical ranges and then cooling in water, oil, or air as desired. For man purposes for which this alloy steel is adap it will be desirable to vary the physical pro-- perties by heat treatment which may consist of hardening as mentioned and drawing the steel by re-heating after such hardening.

I claini- 1. As a new product, an alloy steel comprising, chromium from 1.0% to 10.0%, silicon from 0.5% to 6.0%, aluminum from 0.2% to 6.0%, copper from 0.5% to 5.0%, carbon from 0.05% to 1.0%, and the balance iron.

2. An allo steel comprising as alloying ingredients t ereof, chromium from 1.0% to 10.0%, silicon from 0.5% to 6.0%, aluminum Ifsrom 0.1% to 6.0%, and copper from 0.5% to 3. A stable surface alloy having, as alloy-- ing elements, about 1 to 10% of chromium, about 0.5 to 6% of silicon, about 0.1 to 6% of aluminum, about 0.5 to 5% copper and up to about 1% of carbon, the balance being mainl iron.

4. alloy steel having, as-allo ingredi'ents, silicon 0.5% to 6% and aluminum 0.2% to 6%, the silicon an aluminum forming together from 4% to 6% of the total, and, as other alloying elements, chromium from 1% to 10% and copper from 0.5% to 5%.

5. An alloy steel having, as alloying ingredients, chromium from 1% to 10%, silicon 0.5% to 6%, aluminum 0.2% to 6% and cop or 0.5% to 5%, the combined content of t e silicon and aluminum being between 2.5% and 6.2%.

6. An alloy steel having, as allo ingredients, chromium from 1% to 3%, 81 con 0.5% to 6% and aluminum 0.2% 110.6% and the two together amounting to from 5% to 6.21%, copperfrom 2% to 5%.

testimony whereof I have signed my name to this specification.

RALPH P. DE VRIES. 

